The Vatican has miserably failed the victims of child sex abuse within the Catholic Church, the Deputy First Minister has claimed.

As calls continue for Irish Primate Cardinal Sean Brady to resign over his involvement in a Church investigation that failed to stop paedophile priest Brendan Smyth's reign of abuse, Martin McGuinness shifted focus to Rome's attitude to historical clerical sex crimes.

“The issue of Cardinal Brady's position in all of this is important for a lot of people. But of more importance to me is the attitude that pertains in the Vatican,” said the Sinn Fein politician.

Mr McGuinness hit out at how Rome had approached previous inquiries into abuse scandals and warned the Catholic authorities that if they failed to co-operate with a forthcoming investigation into institutional abuse in Northern Ireland, they would be compelled to do so.

Mr McGuinness has urged Cardinal Brady to reflect on his position, but during Assembly question time he said he was more concerned with the attitude of the Vatican to clerical sex abuse.

Commenting on recent action taken by the Church to censure outspoken liberal clerics, among them the high-profile Co Fermanagh author and journalist Father Brian D'Arcy, Mr McGuinness accused the Church of trying to silence progressive priests and deflect attention away from Church failings.

Addressing the Assembly, Mr McGuinness supported calls from Dublin Archbishop Diarmuid Martin, whom he described as a “colossus”, for a specific inquiry into the Smyth case.

“He is someone who understands absolutely what is going on and what is required to put it right, and of course he has called for the establishment of a commission of inquiry North and South into the Father Brendan Smyth case,” he said.

“So that is something that we have to take on board because I think that the trail of destruction, which it appears lasted from well before 1975 right through to the early 1990s, raises all sorts of questions as to how this monster was handled by the Catholic Church.”

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A BBC documentary last week uncovered revelations about an internal Catholic Church investigation into notorious paedophile priest Brendan Smyth in 1975. Cardinal Brady, then a 36-year-old priest, was involved in an interview with victim Brendan Boland, then a teenage boy, when he outlined Smyth's crimes and gave the names of other children who were at risk.

The cleric passed the allegations to his superiors but did not inform police or the children's parents. Dr Brady has said he now realises that the parents of children who were being abused should have been told of the allegations.